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Ab Initio direct classical trajectory investigation on the S N 2 reaction of F − with NH 2 F: Nonstatistical central barrier recrossing dynamics
Author(s) -
Yu Feng
Publication year - 2011
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.21979
Subject(s) - chemistry , intramolecular force , intermolecular force , transition state , potential energy surface , ab initio , transition state theory , kinetic energy , computational chemistry , molecular dynamics , trajectory , potential energy , ab initio quantum chemistry methods , reaction dynamics , kinetics , atomic physics , molecule , stereochemistry , physics , reaction rate constant , quantum mechanics , catalysis , biochemistry , organic chemistry
The bimolecular nucleophilic substitution (S N 2) reaction of F a − with NH 2 F b has been investigated with the ab initio direct classical trajectory method. According to our trajectory calculations, a dynamic behavior of nonstatistical central barrier recrossing is revealed. Among the 64 trajectories calculated in this work, 45 trajectories follow the dynamic reaction pathways as assumed by statistical theory and other 19 trajectories with central barrier recrossings are nonstatistical. For the nonstatistical trajectories, the central barrier recrossings may originate from the inefficient kinetic energy transfer from the intramolecular modes of the NH 2 F a moiety in the dynamic F b − … HNHF a complex to the intermolecular modes of the dynamic F b − … HNHF a complex on the exit‐channel potential energy surface. With respect to the dynamic behavior of the nonstatistical central barrier recrossing, the statistical theories such as the Rice‐Ramsperger‐Kassel‐Marcus and transition state theories without further corrections cannot be used to model the reaction kinetics for this S N 2 reaction. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2012